The recent advent of fluorescence labeling in the field of medicine has led to advanced imaging techniques. These techniques involve the injection of organic fluorophore labeled compounds at the site of target tissue to be examined, such as the site of suspected cancerous animal tissue. Following injection, the fluorophores will tend to accumulate in cancerous tissue in greater concentrations than in non-cancerous tissue. Fluorescence instrumentation is used to detect the accumulated fluorophores and, in turn, identify suspected cancerous tissue.
Fluorescence labeling uses organic fluorophores that are configured to absorb an excitation light at characteristic frequencies for the fluorophore and then emit light having a longer wavelength, also characteristic for the specific fluorophore. Quantum dots, a semiconductor fluorescence marker, have also been used to label organic molecular structures. The quantum dots may be excited at broader wavelengths of light than fluorophores, but like their organic counterparts, emit light having a predetermined characteristic frequency. As fluorescence tagging and imaging becomes more common in the clinical setting, instrumentation to provide excitation and emission detection in a quantitative manner is needed.
Most available fluorescence instrumentation is intended for microscopic applications of ex vivo specimens. To date, in vivo applications have been limited to superimposed images of fluorescence emissions to detect, for example, blood flow and lymphatic structures. Available instruments are relatively large and cumbersome, resulting in limited clinical use. There is a need for a way to more broadly utilize fluorescence labeling in connection with in vivo applications.